This invention relates to the fitting and fabrication of hearing aids and more particularly to an earmold suitable for use with hearing aid electronics and to a method of shaping said earmold in situ in a minimum of time and office visits.
A conventional method of fabricating hearing aids with external receivers is to first prepare a standard custom-made earmold from, for example, an acrylic material, which is fit with a snap ring that will accommodate external hearing aid receivers. This procedure involves taking an impression of the external auditory canal of the ear and sending this impression to an earmold company which makes a custom-fit earmold. It is then necessary for the individual to return to the office for fitting and evaluation of hearing aids with the custom-fit earmold. Moreover, since it is impossible to predict whether a particular impression will produce an earmold which is capable of forming an adequate acoustic seal so as to reduce feedback, a number of unsatisfactory molds may be made before an acceptable one is produced.
Another procedure for forming an earmold and evaluate hearing is disclosed in U.S. Pat. No. 4,412,096 which provides a combination earmold and receiver adapter which allows a custom-fit earmold to be made and hearing aids to be evaluated within a single office visit. The combination comprises an earmold made of a flexible, elastic, fast-setting silicon material having a density after curing of about 0.5-3.0 gm/cc.
The structure of the receiver adapter allows it to be physically inserted in the earmold before the silicone material completely cures, and allows receivers to be interchanged and tested, within about fifteen minutes of the beginning of the earmold fabrication procedure.
The silicone materials disclosed therein have a curing time of about 10 to 20 minutes at room temperature thereby providing only a relatively short period of time for the fitting of the earmold in situ. Accordingly, it is disclosed therein that the earmolds produced are not normally utilized as permanent hearing aids.
Having an earmold fitting procedure which allows making a custom-fit permanent earmold within a short time and preferably within one office visit, would greatly facilitate the fitting hearing aids, as well as reduce the amount of time spent with each patient.